1. Field of the Invention
The invention relates to fluid-driven torsional operators for turning rotary valves such as butterfly valves, ball valves or the like and for turning other similar devices which include a member that pivots about an axis such as, for example, circuit breakers, tilt mechanisms, and control mechanisms.
The fluid-driven torsional operators embodying the present invention are particularly advantageous for effecting rotary actuation in the angular range from 0.degree. to 100.degree.. If desired, however, these operators can also be used to effect rotary actuation of a greater amount.
The fluid-driven torsional operators which embody the present invention are energized by pressurized fluid which may be compressed air or other gas or vapor or mixture of gases or may be pressurized water or other liquid or mixture of liquids. Thus, such gases as compressed carbon dioxide, nitrogen, steam, or other vapor may be utilized to energize these operators. Additionally, such liquids under pressure as hydraulic fluid may be utilized. Accordingly, as used in this patent application, the terms "pressurized fluid" or "fluid under pressure" are intended to be construed to include compressed air, steam, or other pressurized gas or mixture of gases or vapor or pressurized water, hydraulic fluid or other liquid or mixture of liquids under pressure. In the majority of installations compressed air is the most convenient and practical pressurized fluid to be utilized.
It is also possible to energize the fluid-driven torsional operators which embody the present invention by mounting these operators in an environment having subatmospheric pressure and supplying the operator with input fluid at some pressure higher than that of the environment. Thus, the terms "pressurized fluid" or "fluid under pressure" are also to be construed to include circumstances where the operator is mounted in an environment having subatmospheric pressure, and the input fluid supplied to the operator is at a pressure higher than that of the environment. Thus, the input fluid is pressurized or under pressure relative to the pressure of the environment in which the operator is mounted.
2. Description of the Prior Art
A variety of rotary valve operator apparatus have been previously used to control rotary valves such as ball and butterfly valves. For example, Fisher Governor Company, predecessor to Fisher Controls Company, has marketed a pneumatically operated piston actuator, bearing the trademark "VEE-BALL", which operates on valve members through a piston crank linkage to convert linear motion into rotary motion. A scotch yoke and other mechanical linear-to-rotary motion converters have also been used in conjunction with various linear motion devices such as the pneumatic piston. In addition, electromagnetic and electromechanical operators are also known and used presently to turn rotary valves.
The prior art apparatus of the types reviewed above are generally complicated for providing rotary operation of the valves or other devices, because such prior art apparatus requires conversion of linear motion into rotary motion. In addition, the complex mechanical, electromechanical or electromagnetic operators in the prior art are themselves relatively expensive to manufacture.
The fluid-driven torsional operators which embody the present invention provide rotary motion in a unique and novel manner and they can be mounted so as to operate directly on the valve stem or other device to be turned.
Fluid-driven tension actuators are also presently known. For example, British patent specification No. 674,031 -- Morin discloses a generally cylindrical-shaped diaphragm which includes a plurality of inextensible threads having an extensible deformable resilient sealing element bonded to and extending between the threads. When inflated, the resilient diaphragm changes shape causing changes in the curvature of the threads and hence moving the two rigid end parts towards or away from each other. U.S. Pat. No. 3,645,173 -- Yarlott discloses a fluid actuator with an axially elongated thin-walled, flexible shell. A network of nonelastic strands is embedded in this flexible shell. Upon inflation, the shell radially expands but axially contracts. U.S. Pat. No. 3,638,536 -- Kleinwachter et al. discloses a device having one or more diaphragms with inelastic filaments embedded in them to impart anistropic elasticity to the diaphragm. Anistropic elasticity may also be achieved by using secondary diaphragms that cannot be stretched by crimping or corrugating and embedding them in a flexible diaphragm. This device may then be used to convert fluid pressure into linear motion. In FIG. 7 of Kleinwachter et al. the diaphragm when inflated has the shape of a doughnut or toroid, generally resembling that of an inflated pneumatic tire, and the filaments extend obliquely across the radial direction between hub and rim, thereby producing torsion when inflated. However, because the Kleinwachter et al filaments extend in a near-radial direction, the angular motion is severely restricted.